The present invention relates to a technology for amplifying an electric signal.
As shown in FIG. 6, there is disclosed in, e.g., JP-A-5-347519, an amplifying device 90 having a charge pump circuit 94 for generating a positive side power source potential VA and a negative side power source potential VB which are supplied to an amplifier 92. The charge pump circuit 94 generates the negative side power source potential VB by reducing the positive side power source potential VA supplied from the outside, and supplies the negative side power source potential VB to the amplifier 92.
However, in the technology of JP-A-5-347519, there is a problem that it is difficult to increase an output amplitude (increase an output) and, at the same time, reduce power consumption. Specifically, when the positive side power source potential VA is reduced in order to reduce the power consumption, the output amplitude is also reduced, while when the positive side power source potential VA is increased in order to increase the output amplitude, the power consumption is also increased.